angular.module('myApp', [])
    .controller('MyController',function($scope,$interpolate){
        $scope.$watch('emailBody',function(body){
            console.log(body);
            if(body){
                var template = $interpolate(body);//返回的template是一个function
                $scope.previewText = template({to:$scope.to});
            }
        })
    })